electrolytes

Fluid Compartments

• There are three main fluid compartments: intracellular fluid (ICF), extracellular fluid (ECF), and transcellular fluid.
• Intracellular fluid (ICF) is the fluid within cells, making up 42% of body weight and 2/3 of body water.
• Extracellular fluid (ECF) is the fluid outside cells, divided into intravascular (plasma) and interstitial fluid (between cells, including lymph).
• Transcellular fluid is a small but important fluid compartment, making up approximately 1 liter.

Intracellular Fluid (ICF)

• ICF is the fluid within cells, making up 42% of body weight and 2/3 of body water.
• Potassium (K+) is the most prevalent intracellular cation.
• Phosphate (PO4-) is the most prevalent intracellular anion.

Extracellular Fluid (ECF)

• ECF is the fluid outside cells, divided into intravascular (plasma) and interstitial fluid (between cells, including lymph).
• Chloride (Cl-) is the most prevalent anion in interstitial fluid.
• Sodium (Na+) is the most prevalent cation in interstitial fluid.
• 2/3 of ECF is in interstitial fluid, and 1/3 is intravascular.

Transcellular Fluid

• Transcellular fluid is a small but important fluid compartment, making up approximately 1 liter.
• It includes cerebrospinal fluid (CSF), gastrointestinal (GI) tract fluid, pleural space fluid, synovial spaces, and peritoneal space fluid.

Mechanisms Controlling Fluid and Electrolyte Movement

• Diffusion: the movement of molecules from an area of high concentration to an area of low concentration.
• Facilitated diffusion: the movement of molecules with the help of carrier molecules.
• Active transport: the movement of molecules against their concentration gradient, requiring energy (e.g., keeping sodium out and potassium in cells, using ATP).

Osmosis and Hydrostatic Pressure

• Osmosis: the movement of water between compartments separated by a membrane, from an area of high water concentration to an area of low water concentration.
• Hydrostatic pressure: the force within a fluid compartment.
• Oncotic pressure (colloid osmotic pressure): the osmotic pressure exerted by colloids (e.g., proteins) in a solution, pulling fluid into the vascular space.

Fluid Shifts and Edema

• Fluid shifts can occur from plasma to interstitial space, resulting in edema.
• Causes of fluid shifts include elevated venous hydrostatic pressure, decreased plasma oncotic pressure, and elevated interstitial oncotic pressure.

Electrolyte Disorders

• Electrolyte imbalances can occur due to excess or deficit of sodium, potassium, calcium, and magnesium.
• Signs and symptoms of electrolyte disorders vary depending on the specific electrolyte and whether it is in excess or deficit.

Protein Imbalances

• Plasma proteins, especially albumin, are important determinants of plasma volume.
• Hyperproteinemia is rare and occurs with dehydration-induced hemoconcentration.
• Hypoproteinemia can occur due to various causes, including anorexia, malnutrition, starvation, fad dieting, poorly balanced vegetarian diets, poor absorption, inflammation, and hemorrhage.

Hypoproteinemia Clinical Manifestations

• Edema due to insufficient oncotic pressure.
• Slow healing, anorexia, fatigue, anemia, muscle loss, and ascites.
• Management involves a high-carbohydrate, high-protein diet, dietary protein supplements, and enteral or total parenteral nutrition.

Extracellular Fluid Volume Imbalances

• Hypovolemia can occur due to loss of normal body fluids, decreased intake, or plasma-to-interstitial fluid shift.
• Hypervolemia can occur due to excessive intake, abnormal retention of fluids, or interstitial-to-plasma fluid shift.
• Management involves fluid replacement, diuretics, and fluid restriction.

Nursing Diagnoses and Implementation

• Nursing diagnoses for hypervolemia include excess fluid volume, ineffective airway clearance, risk for impaired skin integrity, and disturbed body image.
• Nursing diagnoses for hypovolemia include fluid volume deficit, decreased cardiac output, and risk for impaired skin integrity.
• Nursing implementation involves monitoring intake and output, cardiovascular status, respiratory status, neurological function, and daily weights, as well as assessing skin turgor and edema.